Iranian Foreign Minister Ali Akbar Salehi has expressed optimism over the current visit of a team of UN nuclear experts tasked with answering pressing questions about Tehran's disputed atomic program.

The experts from the International Atomic Energy Agency (IAEA) are in Iran until January 31.

An IAEA report in November said some aspects of the program could only have military applications.

Salehi said he wasn't expecting "miracles" as a result of the visit but said it was a "first step."

"So I would in a nutshell say that I am optimistic about this visit," Salehi said. "Of course I do not mean that a miracle will happen overnight, but you know a long journey starts with the first step."

Salehi also said the IAEA team could visit all nuclear sites during their visit.

U.S. Defense Secretary Leon Panetta has said analysts believe that Iran could develop a nuclear weapon within about one year if Tehran decided to do so.

Speaking on the CBS “60 Minutes” program broadcast on January 29, Panetta said it would probably take Iran another two to three years to produce a missile or other vehicle that could deliver the weapon to a target.

Panetta's comments came with a team of inspectors from the United Nations' nuclear watchdog agency, the International Atomic Energy Agency (IAEA), at work in Iran.

Panetta reiterated that the United States does not want Iran to develop a nuclear weapon. He called this a “red line” for both the U.S. and its ally Israel.

"If they proceed and we get intelligence that they are proceeding with developing a nuclear weapon, then we will take whatever steps are necessary to stop them," he said.

The IAEA team began talks with Iranian nuclear officials on January 29, although few details have emerged.

Ahead of the visit, the chief of the IAEA team, Herman Nackaerts, urged Iran to work with the mission, saying such cooperation is long overdue.

Iran's parliamentary speaker, Ali Larijani, characterized the visit as a "test" for the IAEA, saying Iran would cooperate if the IAEA acted "professionally" and not as "a tool of the West."

There has been speculation the IAEA experts could visit a mountain bunker at Fordow near the holy city of Qom, although IAEA officials have played down such reports.

At Fordow, Iran says it has enriched uranium to 20 percent for use in a medical reactor in Tehran.

The IAEA arrived as the Iranian parliament delayed a vote on a proposed bill to stop shipping oil to the European Union, its second-biggest customer. It was unclear when parliament would take up the bill.

The measure is a reaction to a recent EU vote to impose an oil embargo on Iran and freeze assets of its central bank.

The United States has taken similar action to pressure Iran to rein in its nuclear ambitions.

Quoted by the official IRNA news agency, Iranian state oil company head Ahmad Qalehbani said pressures on Iran's oil exports could drive prices as high as $150 a barrel.

Iranian Oil Minister Rostam Qasemi was quoted by IRNA as saying oil exports to some unspecified countries would soon be cut.

Qasemi said Iran "will not face any problems" selling its oil to countries outside Europe.

In Chicago, Indian Finance Minister Pranab Mukherjee said his country, which gets 10 percent of its oil from Iran, will not cut its Iranian imports.